X-Git-Url: http://git.ithinksw.org/philo.git/blobdiff_plain/46fdca9049d4b7806bc4d6ec33973a3fc19153c4..3c26965045e8881acd4d5de8c195e4aa61b95ed1:/validators.py

diff --git a/validators.py b/validators.py
index 637dba8..5ae9409 100644
--- a/validators.py
+++ b/validators.py
@@ -1,6 +1,19 @@
 from django.utils.translation import ugettext_lazy as _
 from django.core.validators import RegexValidator
+from django.core.exceptions import ValidationError
+from django.template import Template, Parser, Lexer, TOKEN_BLOCK, TOKEN_VAR, TemplateSyntaxError
+from django.utils import simplejson as json
+from django.utils.html import escape, mark_safe
 import re
+from philo.utils import LOADED_TEMPLATE_ATTR
+
+
+INSECURE_TAGS = (
+	'load',
+	'extends',
+	'include',
+	'debug',
+)
 
 
 class RedirectValidator(RegexValidator):
@@ -28,3 +41,119 @@ class URLLinkValidator(RegexValidator):
 		r'|)' # also allow internal links
 		r'(?:/?|[/?#]?\S+)$', re.IGNORECASE)
 	message = _(u'Enter a valid absolute or relative redirect target')
+
+
+def json_validator(value):
+	try:
+		json.loads(value)
+	except Exception, e:
+		raise ValidationError(u'JSON decode error: %s' % e)
+
+
+class TemplateValidationParser(Parser):
+	def __init__(self, tokens, allow=None, disallow=None, secure=True):
+		super(TemplateValidationParser, self).__init__(tokens)
+		
+		allow, disallow = set(allow or []), set(disallow or [])
+		
+		if secure:
+			disallow |= set(INSECURE_TAGS)
+		
+		self.allow, self.disallow, self.secure = allow, disallow, secure
+	
+	def parse(self, parse_until=None):
+		if parse_until is None:
+			parse_until = []
+		
+		nodelist = self.create_nodelist()
+		while self.tokens:
+			token = self.next_token()
+			# We only need to parse var and block tokens.
+			if token.token_type == TOKEN_VAR:
+				if not token.contents:
+					self.empty_variable(token)
+				
+				filter_expression = self.compile_filter(token.contents)
+				var_node = self.create_variable_node(filter_expression)
+				self.extend_nodelist(nodelist, var_node,token)
+			elif token.token_type == TOKEN_BLOCK:
+				if token.contents in parse_until:
+					# put token back on token list so calling code knows why it terminated
+					self.prepend_token(token)
+					return nodelist
+				
+				try:
+					command = token.contents.split()[0]
+				except IndexError:
+					self.empty_block_tag(token)
+				
+				if (self.allow and command not in self.allow) or (self.disallow and command in self.disallow):
+					self.disallowed_tag(command)
+				
+				self.enter_command(command, token)
+				
+				try:
+					compile_func = self.tags[command]
+				except KeyError:
+					self.invalid_block_tag(token, command, parse_until)
+				
+				try:
+					compiled_result = compile_func(self, token)
+				except TemplateSyntaxError, e:
+					if not self.compile_function_error(token, e):
+						raise
+				
+				self.extend_nodelist(nodelist, compiled_result, token)
+				self.exit_command()
+		
+		if parse_until:
+			self.unclosed_block_tag(parse_until)
+		
+		return nodelist
+	
+	def disallowed_tag(self, command):
+		if self.secure and command in INSECURE_TAGS:
+			raise ValidationError('Tag "%s" is not permitted for security reasons.' % command)
+		raise ValidationError('Tag "%s" is not permitted here.' % command)
+
+
+def linebreak_iter(template_source):
+	# Cribbed from django/views/debug.py
+	yield 0
+	p = template_source.find('\n')
+	while p >= 0:
+		yield p+1
+		p = template_source.find('\n', p+1)
+	yield len(template_source) + 1
+
+
+class TemplateValidator(object): 
+	def __init__(self, allow=None, disallow=None, secure=True):
+		self.allow = allow
+		self.disallow = disallow
+		self.secure = secure
+	
+	def __call__(self, value):
+		try:
+			self.validate_template(value)
+		except ValidationError:
+			raise
+		except Exception, e:
+			if hasattr(e, 'source') and isinstance(e, TemplateSyntaxError):
+				origin, (start, end) = e.source
+				template_source = origin.reload()
+				upto = 0
+				for num, next in enumerate(linebreak_iter(template_source)):
+					if start >= upto and end <= next:
+						raise ValidationError(mark_safe("Template code invalid: \"%s\" (%s:%d).<br />%s" % (escape(template_source[start:end]), origin.loadname, num, e)))
+					upto = next
+			raise ValidationError("Template code invalid. Error was: %s: %s" % (e.__class__.__name__, e))
+	
+	def validate_template(self, template_string):
+		# We want to tokenize like normal, then use a custom parser.
+		lexer = Lexer(template_string, None)
+		tokens = lexer.tokenize()
+		parser = TemplateValidationParser(tokens, self.allow, self.disallow, self.secure)
+		
+		for node in parser.parse():
+			template = getattr(node, LOADED_TEMPLATE_ATTR, None)
\ No newline at end of file